docs: def com_google_fonts_check_family_panose_proportion(ttFonts):
    """Fonts have consistent PANOSE proportion?"""
    failed = False
    proportion = None
    for ttFont in ttFonts:
      if proportion is None:
        proportion = ttFont['OS/2'].panose.bProportion
      if proportion != ttFont['OS/2'].panose.bProportion:
        failed = True
  
    if failed:
      yield FAIL, ("PANOSE proportion is not"
                   " the same accross this family."
                   " In order to fix this,"
                   " please make sure that the panose.bProportion value"
                   " is the same in the OS/2 table of all of this family"
                   " font files.")
    else:
      yield PASS, "Fonts have consistent PANOSE proportion."